(a) Field of the Invention
The present invention relates to a method and an apparatus for transmitting pilots in a multi-antenna communication system. The present invention also relates to a method and an apparatus for allocating pilots in a multi-antenna communication system.
(b) Description of the Related Art
A MIMO (multiple input multiple output) technology has been extensively used to increase a communication capacity in a communication system. A system according to a LTE (long term evolution)-A (advanced) standard that is a cellular mobile communication system standard may transmit 8 streams by using 8 antenna ports.
Data that is beam-formed may be transmitted by sharing OFDM (orthogonal frequency division multiplexing) symbols and subcarrier resources, and pilot signals may also be transmitted through the same beam-forming as the data in the 8 antenna ports. In this regard, the pilot signals (or pilots) may be transmitted along with the data only when the data is transmitted.
Meanwhile, due to a recently rapid increase in wireless traffic, research into an application of a millimeter wave (mmWave) band having an available frequency bandwidth wider than that of a frequency band used in the existing cellular mobile communication to mobile communication has been carried out in a standardization organization such as a 3GPP (3rd generation partnership project) and a mobile communication industry.
Use of a high frequency such as the millimeter wave, etc. may enable a reduction in an antenna size. The reduction in the antenna size may allow a base station to mount a greater number of antennas than the existing number of antennas.
The base station may transmit a plurality of fixed beams or adaptive beams within a sector through a plurality of antennas. The plurality of antennas may also enable to manage a 3D (3 dimensional) beam-forming base station system.
Meanwhile, the base station needs a plurality of pilots to transmit traffic data through a plurality of beams. However, an independent allocation of pilots as many as increased beams may act as an overhead of an entire system, which deteriorates a communication capacity. Therefore, it is important to design and manage pilots.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.